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%I #17 Sep 08 2022 08:46:10
%S 2,5,9,10,16,30,21,28,20,43,38,60,36,66,68,40,55,62,60,104,75,101,82,
%T 176,52,108,108,132,100,203,93,120,144,136,148,124,96,186,144,250,136,
%U 264,126,244,192,217,170,240,122,148,227,195,172,378,235,384,222,262,226,496,156,282,246,160,272,423,192,344,296,427
%N a(n) = phi(n) + sigma(sigma(n)).
%C If n is a Mersenne prime then a(n) = 3n (see comments in A000668).
%F a(n) = A000010(n) + A000203(A000203(n)) = A000010(n) + A051027(n).
%t Table[EulerPhi[n]+DivisorSigma[1,DivisorSigma[1,n]],{n,70}] (* _Harvey P. Dale_, Feb 27 2020 *)
%o (Magma) [EulerPhi(n) + SumOfDivisors(SumOfDivisors(n)) : n in [1..100]]; // _Vincenzo Librandi_, Nov 15 2014
%o (PARI) vector(100,n,eulerphi(n)+sigma(sigma(n))) \\ _Derek Orr_, Nov 15 2014
%Y Cf. A000010, A000203, A000668, A008585, A051027, A065387.
%K nonn,easy
%O 1,1
%A _Omar E. Pol_, Nov 14 2014
%E Corrected and extended by _Harvey P. Dale_, Feb 27 2020
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